


Genocide Is a Poison

by GlowPOP_Artisan



Category: Undertale (Video Game)
Genre: Affection, Blood, Brotherly Bonding, Brotherly Fluff, Daddy Kink, Dominant Sans, Dreams and Nightmares, Echo goes Genocidal, Ecto-Penis, Ecto-Tongue, Eventual Smut, F/F, F/M, Female Frisk, Fluff and Hurt/Comfort, Fluff and Smut, Fondling, Genocide Route, Genocide Sans, Gentle Kissing, Gentle Sex, Gentleness, Human/Monster Romance, Intense, LET THERE BE SMUT, Love, Nightmares, Painful Sex, Possessed Echo, Sans Makes Puns, Sexual Content, Shower Sex, Sibling Bonding, Smol Frisk, Some Characters Die, Step-siblings, Tentacle Rape, Threats of Violence, Violent Thoughts, Warm and Fuzzy Feelings, Worried Sans, body separation, ecto tentacles, small vagina, straight smut, there will be smut, unintentional hurt
Language: English
Status: In-Progress
Published: 2016-05-17
Updated: 2016-05-17
Packaged: 2018-06-08 23:22:21
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 823
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6879115
Author URL: https://archiveofourown.org/users/GlowPOP_Artisan/pseuds/GlowPOP_Artisan
Summary: <blockquote class="userstuff">
              <p>Finally back on the surface, and living alongside the monsters that they had befriended while in the Underground, the Wildberries can finally rest. Unknown to her newfound family, Echo starts having nightmares of what would've happened if the embodiment of a killer went and controlled her to kill off the Underground. And what will happen when it forms a mind and body of its own?</p>
            </blockquote>





	Genocide Is a Poison

It started...the nightmares, the visions, the jumpiness at every turn, it was something that was hard to control. 

Echo couldn't piece together what had taken place in that mind of hers. No matter what she did to try and stay calm, she couldn't bring herself to take a chill pill. Even Sans noticed, and her sister, Ginger Rose as well. Echo kept having thoughts of genocide and couldn't even manage a smile. Her hesitation and apathy were slowly showing. 

That night, when Papyrus and Gingi were in the kitchen, Echo was sitting with Sans, Toriel, Asgore and Frisk while waiting for tonight's helping of ravioli and tasty Italian bread. Frisk could smell the bread from the kitchen and she licked her lips as Toriel and Sans chuckled. Asgore offered a friendly smile at Echo as she smiled back. 'Alphys and Undyne are late...' Echo thought to herself as she looked around the room at a 180 degree angle, then she sat back down. 

"My child...Echo, is everything OK?" Toriel asks as Frisk reveals a look of worry, giving her big stepsister a hug. Echo smiled and tried so hard not to cry, Sans could even feel her holding back, patting her back as Frisk was close to crying too. 

"Big sister....?" Frisk asked as she tried to comfort Echo. "Sissy, don't cry..."  
"Leave it to me, Frisk." Sans said, stroking her hair and holding Echo's hand. "E, come with me for a sec." 

"Awww, Sans, right now? Dinner's gonna be ready soon."  
"I'm serious; follow me." his blue eye was practically in full glow as they both stepped into the hallway. He gently pressed his skull against her forehead and planted a soft toothy kiss there. Now his eye was glowing a calm green. "Alright, tell me what's going on." 

Echo looked at Sans with a nervous smile. "Sans....remember when you said you wouldn't berate me if I told you anything....odd? Or even disturbing?"  
"Echo, I've seen enough to know the definition of disturbing. Papyrus or one of my close friends being murdered as one of them...or if something terrible were to happen to you. I would never forgive myself." he squeezed her hand softly and wrapped it protectively around his phalanges as Echo let some tears escape. 

"I was having thoughts of genocide, Sans." she whispered softly as Sans felt the blue in his eye slowly appear as he squeezed her hand tighter. He looked down at her and pushed her hard against the wall, pinning her. 

"Yessss, I've noticed." Sans hissed as he hit her head against the wall. "Hell, I could smell it on ya~ You nearly killed everyone. Papyrus, Undyne, Asgore.....Tori...you were a sick lil' freak, weren't you?!" 

Echo screamed as Sans noticed that she was scared, snapping out of his trance and hugging her close. "E-Echo...hun....I'm so sorry....I just....oh god...I had no idea how scared you would be if I...ugh...I'm so sorry..." he hugged her small body as she wailed more. "Ssh-ssh-ssh, it's OK...it won't happen again...trust me on that..." he stroked her plum colored hair and wiped her tears away. 

"Daddy....I mean, Sans...I've trusted you since you and Pap took me and my sister in. You've done nothing to hurt me, and I can promise you, my opinion on you has not changed. I could hardly give two HP if you were human or a monster! The inside is what counts, or rather in your case, the SOUL is what matters! So don't blame yourself for what you did, it was deserved since I said....'that' unintentionally." 

Sans got a boost from that and kissed her gently.  
"SANS! KEIKOSAN! DINNER!!" Papyrus' voice boomed from the dining room as the two walked together, Sans going back to saying puns and drumming up some stand-up comedy that rattled Papyrus' bones to the point where he went to bed early after doing the dishes. Ginger went after him, and the two went upstairs together.

"Geez, Pap was a sour apple about your puns, Sans." Echo giggled as they got ready for bed.  
"They really drove him to the CORE." Sans chuckled. "I'm LICHEN the fact that you think I'm a pretty PUNNY guy~" and he got his sweet little human chuckling and she kissed him lovingly. 

"Knock, knock~"  
"Who's there?~" Sans asked.  
"Chew~"  
"Chew who?~"  
"Chew got anymore puns before we go to bed?~" Echo giggled as Sans kissed her neck softly. "No?~ What does Daddy have in mind?~" 

"Oh, your legs are gonna feel like jelly when I'm through with you~ I'm gonna bone you tonight, Echo~ So be ready~" he kissed her lovingly and caressed her sides as she moaned for him. "Call me Daddy tonight~" he added as he licked her softly with his gelatinous blue tongue.

Echo could feel that she wasn't far from having a good time.

**Author's Note:**

> Finally!~ I got another Undertale fic in progress~~ Hope you enjoy and stay tuned for Chapter Five of my Underfell fanfic coming this weekend~


End file.
